AHU operation schedule, and setback

thoee7 · Posts: 1

Hi!

Please help me with these questions .

I’ve created this project with ver1.2.2 002 and now, I am using ver 1.4.

1.My building HVAC is VAV reheat with compact system.
What does AHU operation schedule mean?
When I turn that schedule "off", it seemed like the chiller and boiler(thus, cooling and heating themselves) do not operate.
If the AHU operation is mandatory for heaing and cooling operation, how should I balance between the schedule for heating(or cooling) operation schedule and the schedule for AHU coil heating(or cooling)? Should I just make those schedules match
each other?

2. For the heating or cooling schedule, if I only schedule for office hour(for say, 8-18pm mon-fri), does the set-back setpoint will be applied to the
"non-scheduled" hours? According to my observation, for the hours the heating or cooling operation is not scheduled (for example, set as 0 for compact schedule
option or not scheduled for 7/12 schedule option), the set-back point I typed under the Activity tab doesn't work.

3. And, Let's say that I set cooling setpoint 24C and heating setpoint 21C. My understanding is that, if the thermostat read the indoor temperature as 23C, both heating and cooling should NOT operate as if the 21-24C range is a 'dead-band.' Is that right?

Thank you for taking your time.

Please let me know.

Kim

Laurent_Support · Posts: 275 Location: Vincennes

Hello,

1. AHU operation schedule
It controls the supply air. In VAV heating and cooling coils are into the AHU so when you don't blow air you can't heat or cool the zones.
This is the VAV diagram: http://www.designbuilder.co.uk/programhelp/_vav.htm

Heating and cooling schedules manage the coil operations.

2. Schedule and setback temperature
When using a schedule you must enter the setpoints for each period.
Please read this to set your schedule: http://www.designbuilder.co.uk/programhelp/defining_setpoint_temperature_schedules.htm

3. Heating and cooling setpoint
This depends from the heating and cooling schedule. They can operate in the same time (!!) if don't set their activity period exclusively. For example Winter for Heating schedule and Summer for cooling one.

Laurent

sezzeldin · Posts: 14

Hello Laurent,

2. Schedule and setback temperature
How to enter the setpoints for each period?
I read "defining_setpoint_temperature_schedules" to set a schedule but couldn't succeed to set that schedule
Could you please help?
regards,
Sherif

Laurent_Support · Posts: 275 Location: Vincennes

Hello Sherif,

Setpoint value is unique (for instance 16°C) and set in the Activity tab.
The schedule is used to choose what setpoint you want for each period: normal setpoint, setback setpoint or Off.

Now, to define the setpoint schedule, I suggest to follow the documentation, if for time you need to heat/cool at setback temperature, enter 0.5 in the schedule or 50% if you're in 7/12 with profiles.

Laurent

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